Interactions within a polypeptide or protein or between a biomacromolecule and a ligand will be studied, primarily with resonance Raman and Fourier transform infrared spectroscopy. Possible structues of acyl-enzyme intermediates in proteolytic enzymes, such as elastase or chymotrypsin, will be probed. The formation of Schiff base adducts in aldolase, phosphorylase and delta-aminolevulinate will be examined. Intramolecular interactions of tyrosine and of tryptophan residues in proteins and in the morphinomimetic interactions of tyrosine and of tryptophan residues in proteins and in the morphinomimetic oligopeptides (endorphins and enkephalins) will be explored. The nature of intermolecular bonds between polynucleotides and intercalating compounds will be scrutinized. These spectroscopic investigations should provide insights into the nature of the bonding interactions in conformational changes of biological macromolecules and in binding of ligands.